The demand for increased performance of zoom lenses in recent years has resulted a variety of types of zoom lenses. In particular, zoom lenses for electronic image equipment, such as video cameras and digital still cameras, have employed to date so-called Yamaji-type zoom lenses and four-group type zoom lenses having an objectwise to imagewise positive-negative-positive-positive refractive power arrangement. However, these types of zoom lenses are disadvantageous because satisfactory imaging performance at an intermediate focal length state, as well as satisfactory correction of distortion, is not ensured.
With the progress in lens mechanical technology in recent years, zoom lens types having five or more lens groups have been proposed. However, it has proven extremely difficult to simultaneously achieve superior imaging performance, an increased field of view, an increased variable power (i.e., an increased zoom ratio), a compact size, and the like.